Various hydraulic power systems employing a buoyant element or elements that cyclically move in response to rising and falling level of liquid within a receptable in which the buoyant element is located have been attempted in the prior art. Exemplary patents describing such systems include: U.S. Pat. No. 1,264,759; U.S. Pat. No. 1,451,580; U.S. Pat. No. 1,496,470 and U.S. Pat. No. 3,084,905.
Such prior art systems have certain disadvantages which the present invention overcomes. The major disadvantages of the prior art systems are that they require a substantial flow of water through the system for each cycle of operation; the power output of the system is difficult to govern; the power available during the downstroke of the buoyant element is usually smaller than during the upward stroke; the timing of power cycles is limited by the length of time required to fill an empty receptable to vary the level of liquid therein; and multiple buoyant elements arranged to operate in timed relationship are generally required for efficient sustained operation.